应用厚靶实验方法测量电子碰撞内壳层电离截面的深入研究

The experimental data of atomic inner-shell ionization cross-sections by low-energy electron impact is significant for a lot of applications in atom physics, radiation physics, plasma physics, atmosphere physics, material analysis, dose simulation and so on. Up to now, the measurment are mostly carried out by thin-target method, which is difficult to manufacture and the thickness detemination of thin target is significant to the results,meanwhile the most experimental data focuse on the K-shell. Iin this study, based on the the thick-target method tried in the former work , the experimental setup have been adopted with higher resolution , and the experimntal method have been improved, through which the L-, M- shell ionization cross sections by 2-40 keV electron impact will be measured, and K-shell ionization cross sections of a few elements, for which significant discrepancies exist and no data have been reported in the low-energy region, will also be remeasured, so as to obtain more available cross section data for low-energy electron impact to fill the gap of L- and M-shell data. Meanwhile, in the data processing, the factors that may affect the experimental accuracy ,such as the scattering and bremsstrahlung effect, the target surface roughness，electron escaping and so on, are discussed with the combination of analytic calculation and Monte Carlo simulations. Finally,through the comparison with the thin-target data and theoretical models, the thick-target method will be further developed and improved.

低能电子碰撞原子内壳层电离截面数据在原子物理、辐射物理、等离子体物理、大气物理、材料分析、剂量模拟计算等许多领域都是不可或缺的。目前截面测量多采用薄靶方法，制作困难且薄膜厚度测量对实验结果影响很大，实验数据绝大多数仅限于K壳层。本研究在前期尝试的厚靶方法的基础上，采用分辨率更高的实验装置，改进实验方法，将厚靶方法应用于2-40keV的电子致原子L及M壳层电离截面的测量，并针对数据分歧较大及尚无低能区实验数据的几种K壳层元素进行重新测量，以期获得更多有价值的低能电子碰撞原子的内壳层截面数据，来填补亟缺的L及M壳层实验数据；同时，数据处理方面，采用解析计算和Monte Carlo模拟相结合的方法，对影响厚靶实验测量的各种可能因素，如电子的散射及韧致辐射效应，靶表面粗糙度，电子逃逸率等，进行细致的模拟分析和修正，最终通过实验数据与薄靶方法及理论模型计算结果相对比，来进一步发展和完善厚靶实验方法。

低能电子碰撞原子内壳层电离截面数据在辐射物理、等离子体物理、X射线激光、质谱分析、材料分析、剂量模拟计算等许多领域都是不可或缺的。目前截面测量多采用薄靶方法，制作困难且薄膜厚度测量对实验结果影响很大，实验数据绝大多数仅限于K壳层。本研究在前期尝试的厚靶方法的基础上，采用分辨率更高的实验装置，采用超薄窗的内置X 射线探测器，其能量分辨率从原来的190eV提高到130eV，将厚靶方法应用于2-40keV的电子致原子K-,L-及M-壳层电离截面的测量，目前已测量完成了低、中、高原子序数靶样品内壳层电离截面数据，涉及Mg、Mo、Zn、 Zr、 Cu、Fe、 Ni 、 Pb、 Pt 、Ag等元素；同时，数据处理方面，采用解析计算和PENELOPE模拟相结合的方法，对影响厚靶实验测量的各种可能因素进行了细致的模拟分析，采用Tikhonov正则化反演方法，成功解决了内壳层电离截面计算中所涉及的不适定性问题，结果表明，厚靶方法得到的数据与应用薄靶方法得到的实验值符合的很好，与DWBA 理论值也很一致，我们所采用的厚靶方法是很成功的，进一步发展和完善了厚靶实验方法。